...to add, when i refer to the 'whitebox effect' in acrobat, this is a result of transparency flattening, which is necessary in postscript and also pdf version 1.3 acrobat 4, any other pdf version higher than 1.3 acrobat 4, maintains transparency in the pdf. For an output device to handle these, your rip needs to support transparent pdf's...
...if you are refering to the white halo's around the coins, then that is to do with photoshop cutout, or mask not being quite tight enough...
...a tip for layer masks in photoshop is to apply a stroke layer style to the layer, red normally does good. Then it is easy to see where it needs cleaning up...
...grab a black brush, soft one and paint on the mask, or apply a levels or curve adjustment to the actual mask to fine tune the mask, sharpen it up for example...
Andrew